Improvement in treating oil-wells to remove obstructions to the flow of oil



' within the well.

UNITED STATES PATENT BUTLER e. NOBLE, on BROOKLYN, NEW YORK.

IMPROVEMENT IN TREATING OIL-WELLS TO REMOVE QBSTRUCTIONS TO THE FLOW OFOIL.

Specification forming part of Letters Patent N0. 105,590, dated July 19,1870.

Mode or Process for Increasing the Yield of Petroleum-Oil Wells and I dohereby declare that the following is a full and exact descrip- 1 tion,to wit:

The nature'of my invention consists in removing paraffine or otherobstructing matters] from the seams, issues, or natural ducts of suchwells by the employment of an intense: productive points and continuousheat at the To enable others skilled in the art to adopt and use myinvention, I will proceed to describe the mode by which I accomplish theresults desired.

I Petroleum-oil wells are bored inthe rock formation to a depth of fromtwo hundred to one thousand feet, and are from three to six inches indiameter. Inthe oil regions of Pennsylvania the oil is found in thesand-rock. These sand-rocks occur inseparatestrata and ing oil-wellsknow these points of oil-inflow,.

and, by record kept when the well is bored,

can determine with accuracythe location and extent of all water-courses,gas-flows, and oilflows. The average range of inflow does not exceedtwenty feet of vertical extent.

Many wells, after yielding oil in large quantities, gradually diminishin productiveness,

and ultimately cease to produce in paying.

quantities. This failure in yield is not always because of exhaustion ofsupply, but results from the clogging up of the seams or natural ductsleading into the well-bore by the deposition of paraffine and perhapsother carbonaoeousmatters. Paraffine is of wax-like struct- These scamsor in-' ure, about the consistency of spermaceti. It

melts at a temperature considerably below the boiling-point of water. Itis produced from petroleum by deposition at low temperature.

It is probablethat the carbureted-hydrogen gas, almost always present inoil-wells, is under pressure within the cavities of the rock, and whenit reaches the vicinity of the wellbore it gradually expands, and ofcourse produces a low temperature, favorable to the. deposition ofparaffine.

It is obvious that these depositions must be for the most part in theapertures of the oildncts, within the well or immediately contiguousthereto. Portions of paraffine brought up by the pump often have theimprint and form which indicate this location.

To remove these obstructions and restore the yield of oil, many modeshave been devised. That which is now generally adopted consists inpouring into the well from six to sixty barrels of naphtha or otherlight hydrocarbon for the purpose of dissolving the paraffine. Themethod is attended with some success, and hundreds of wells are keptalive by a weekly dose. The disadvantage is the expense and labor, andas all the naphtha must be pumped out, mingled with the natural oil, thelatter is made of less value. Again, if water be present in sufficientamount to cover wholly or in part the range of inflow, the naphtha failsto reach the points desired. The presence of water also in smallquantities materially aifects the solvent power of these agents.

Attempts have been made to introduce steam and to force hot air into thewell.

These modes involved massive machinery and great expense. The wells haveusually many hundred feet of water, and the heat would be taken up andlost by the well and its contents long before the points of obstructionwere reached, and hence this method pro duced no favorable results.

The torpedo for exploding gunpowder, nitroglycerine, and similar mattersfor the purpose of shattering the well-walls and enlarging the cavity,and thus removing obstructions or making new seams or issues, has beenused with varied results. The violent ruptureof the surrounding wallsmay open new fissures,

but the chances are equal that it would close up the old. Hence, thoughthe production is often increased by this mode, yet wells have beendestroyed and ceased to produce when subjected to this violence.

The use of nitro-glycerine, dynamite, or other highlyexplosive agents isalways attended with risk and danger.

The principal and distinguishing characteristic of my invention is theremoval of paraffine and other matters from the seams, issues, orinflows of the oil-well by the combustion of slow-burning compositions,so disposed as to produce an intense and continuous heat withoutexplosion at the points within the well where these obstructions occur.To eflect this I construct what I denominate a volcanic case. Thesecases are usually of wroughtiron, though other metal or material may beused. The case is cylindrical in form, of any convenient length, and ofsuch diameter as the size of the well requires. There should be anannular space of about one inch around the case when placed within thewell. A well of five -inch bore would require a volcanic case of aboutthree inches diameter. The wells often contain four or five hundred feetof water, and cases must be of sufficient strength to withstand thepressure. The bottom of the case must be closed, and the top providedwith a cap, which is fixed when the case is filled. Near the bottom Imake from three to six lateral vents. The size will vary with the amountof heat required in a given time. In general, the total area of theventaperture should be much less than the area of burning-surface withinthe case.

The case is filled with a slow-burning compound analogous to thatemployed for filling rockets, and well known to persons skilled inpyrotechny. Common granulated gunpowder, reduced to a fine powder, formsa safe and reliable filling. It may be made slower by the admixture offive to twenty per centum of powdered charcoal. Compounds of nitrate ofsoda or nitrate of potash, sixteen parts, and powdered charcoal, sixparts, form a good filling. I do not confine myself to any definitecomposition in the production of such compounds, as they are of greatvariety and well known.

The filling should be well rammed to insure slow and even combustion andto render explosion impossible. The action of slow'burn- 111g compoundsis unlike that of granulated gunpowder or nitro-glycerine. While the hotgases produced are identical, the one evolves immense volumesinstantaneously. The other, burning slowly, may produce an intense andcontinuous heat for a long time, and can hardly be said to be explosive.

Carefully-conducted experiments have demonstrated that slow-burningcompounds analogous to rocket filling, well rammed in cases with smallapertures or vents, will, when ignited, exert a pressure of manythousand pounds to the inch, and produce a heat at the ure of the hotgases.

points of discharge equal to from 600 to 1,200 Fahrenheit, and yet thereis no explosion, the case being strong enough to resist the press- Thecase when filled is closed securely and made tight and impervious towater. The vents are closed externally by placing over them smallpatches of metal or other hard substance, and well secured againstmoisture by wax, rubber, or other suitable material.

For igniting the charge I employ any of the ordinary and well-knownmodes used for ignitin g cartridges or blasts under water. Fulminatesplaced within the case at the bottom may be fired by friction, but Iprefer electric fuses for safety and certainty. The ignition should takeplace at the bottom of the case. An electric fuse may be insertedthrough one of the vents, and properly connected with voltaic battery orelectric apparatus. The connections should be adequately protectedagainst wet to secure insulation. The volcanic case, properly preparedand connected, is let down into the well by a line properly attached toa point immediately below the range of inflow 5 it is then ignited. Assoon as combustion takes place the patches are thrown off and thered-hot gases issue with great force from the lateral vents, impingingdirect against the well walls, displacing the water. The volcanic caseis now, while burning, moved slowly upward, exposing the interiorsurface ofthe well-bore continuously to the action of the blast untilthe upper limit of the range of inflow is reached, after which, if notexhausted, the case may be slowly lowered to the place of beginning, andthus by moving upward and downward the whole range of inflow issubjected to the intense heat.

All aggregations of paraffine must be melted and removed. The force ofthe blast, especially if aided by the pressure of several hundred feetof water, is such as to render the heat effective within and through thefissures and seams of the rock for many feet distant.

All matters which are fusible will be eliminated. The old issues may beenlarged by the intense heat and great pressure, and even new orimperfect ones developed and the way prepared for a more abundantreturning oil-flow.

The advantages of the volcanic mode of treating oil-wells are many andclearly apparcut. The expense is comparatively trifling. The materialfor filling the cases is cheap, easily prepared, and safely transportedand handled. The case can be used many times. For most wells a case ofthree inches diameter and three feet in length will burn for from six toeight minutes, a time amply sufficient to command the whole extent ofinflow.

. I V w 1 I do not confine myself to the particular form of volcaniccase herein described, as many a other forms might serve equallywell,'nor to troleuni-oil wells, substantially as herein described.

2. The use of slow-burning compositions Without explosion for theremoval of paraffine and other obstructing matters from the seams,issues, or inflows of petroleum-oil .Wells, substantially as hereindescribed.

BUTLER G. NOBLE.

Witnesses W. G. SPENCER, W. WATERs.

